Effects of the Cu coating thickness on the interfacial mechanical behavior of the AlN/Ag‒Cu composite structure

Abstract A novel AlN/Ag‒Cu composite structure was prepared by electroplating the Cu coating onto the AlN substrate premetallized by Ag layer. The thickness effects of the Cu coating on the fracture toughness and adhesive strength of the AlN/Ag interface of the composite structure were investigated. The damage evolution and failure mechanism of the AlN/Ag interfaces were simulated by the finite element method. The results showed that the critical fracture energy G IC of the AlN/Ag interface reached the maximum value of 23.28 J/m 2 when the thickness of the Cu electroplating coating was approximately 40 µm, which was increased by about 565% compared with that without the Cu coating. Both the σ max and τ max values of the AlN/Ag interfaces were increased by nearly 150%. The numerical simulation results showed that the stress concentration relief resulted from the electroplated Cu coating near the AlN/Ag interface provided an important contribution to the improvement of the mechanical properties of the AlN/Ag‒Cu composite structure. The interfacial damage of the AlN/Ag structure was delayed by the Cu coating. The load transfer of the AlN/Ag‒Cu composite structure could be improved due to the synergistic deformation ability of the Cu‒Ag bimetallic layer.